Effects of Solute and Vacancy Segregation on Migration of a/4<111> and a/2<100> Antiphase Boundaries in Fe₃Al

The effects of segregation of solute atoms and vacancies on migration of a/4〈1 1 1〉 and a/2〈1 0 0〉 antiphase domain boundaries (APDBs) in stoichiometric Fe3Al at various temperatures are studied using a phase-field model [Koizumi Y, Allen SM, Minamino Y, Acta Mater 2008;56:5861] based on the Bragg–Williams approximation and kinetic parameters determined from experimental data. Boundary mobilities (M) were measured from the boundary velocity of shrinking circular antiphase domains (APDs). In the case of a/4〈1 1 1〉 APDBs, solute atmospheres follow the APDB until the APD vanishes by shrinking to zero radius, and therefore the Ms are always smaller than the intrinsic boundary mobilities because of the solute-drag effect. The M of a/4〈1 1 1〉 APDBs can be enhanced by up to 60% by vacancy segregation. On the other hand, the M of a/2〈1 0 0〉 APDBs is enhanced by only a few per cent. The a/2〈1 0 0〉 APDBs are observed to break away from the solute atmosphere during as the circular ABDBs shrink. The M increases by up to 40% associated with the breakaway, and becomes equal to the intrinsic boundary mobilities even though slight depletion and segregation of Al atoms remain ahead and behind the migrating boundary, respectively

Bacterial rotary export ATPases are allosterically regulated by the nucleotide second messenger cyclic-di-GMP

The widespread second messenger molecule cyclic di-GMP (cdG) regulates the transition from motile and virulent lifestyles to sessile, biofilm-forming ones in a wide range of bacteria. Many pathogenic and commensal bacterial-host interactions are known to be controlled by cdG signaling. Although the biochemistry of cyclic dinucleotide metabolism is well understood, much remains to be discovered about the downstream signaling pathways that induce bacterial responses upon cdG binding. As part of our ongoing research into the role of cdG signaling in plant-associated Pseudomonas species, we carried out an affinity capture screen for cdG binding proteins in the model organism Pseudomonas fluorescens SBW25. The flagella export AAA+ ATPase FliI was identified as a result of this screen and subsequently shown to bind specifically to the cdG molecule, with a KD in the low micromolar range. The interaction between FliI and cdG appears to be very widespread. In addition to FliI homologs from diverse bacterial species, high affinity binding was also observed for the type III secretion system homolog HrcN and the type VI ATPase ClpB2. The addition of cdG was shown to inhibit FliI and HrcN ATPase activity in vitro. Finally, a combination of site-specific mutagenesis, mass spectrometry, and in silico analysis was used to predict that cdG binds to FliI in a pocket of highly conserved residues at the interface between two FliI subunits. Our results suggest a novel, fundamental role for cdG in controlling the function of multiple important bacterial export pathways, through direct allosteric control of export ATPase proteins

Genetic Characterization of Conserved Charged Residues in the Bacterial Flagellar Type III Export Protein FlhA

For assembly of the bacterial flagellum, most of flagellar proteins are transported to the distal end of the flagellum by the flagellar type III protein export apparatus powered by proton motive force (PMF) across the cytoplasmic membrane. FlhA is an integral membrane protein of the export apparatus and is involved in an early stage of the export process along with three soluble proteins, FliH, FliI, and FliJ, but the energy coupling mechanism remains unknown. Here, we carried out site-directed mutagenesis of eight, highly conserved charged residues in putative juxta- and trans-membrane helices of FlhA. Only Asp-208 was an essential acidic residue. Most of the FlhA substitutions were tolerated, but resulted in loss-of-function in the ΔfliH-fliI mutant background, even with the second-site flhB(P28T) mutation that increases the probability of flagellar protein export in the absence of FliH and FliI. The addition of FliH and FliI allowed the D45A, R85A, R94K and R270A mutant proteins to work even in the presence of the flhB(P28T) mutation. Suppressor analysis of a flhA(K203W) mutation showed an interaction between FlhA and FliR. Taken all together, we suggest that Asp-208 is directly involved in PMF-driven protein export and that the cooperative interactions of FlhA with FlhB, FliH, FliI, and FliR drive the translocation of export substrate

An energy transduction mechanism used in bacterial flagellar type III protein export

Flagellar proteins of bacteria are exported by a specific export apparatus. FliI ATPase forms a complex with FliH and FliJ and escorts export substrates from the cytoplasm to the export gate complex, which is made up of six membrane proteins. The export gate complex utilizes proton motive force across the cytoplasmic membrane for protein translocation, but the mechanism remains unknown. Here we show that the export gate complex by itself is a proton–protein antiporter that uses the two components of proton motive force, Δψ and ΔpH, for different steps of the protein export process. However, in the presence of FliH, FliI and FliJ, a specific binding of FliJ with an export gate membrane protein, FlhA, is brought about by the FliH–FliI complex, which turns the export gate into a highly efficient, Δψ-driven protein export apparatus

〔論文〕移住外国人女性における生活構造の脆弱性に関する研究 ―子育ての担い手としての立場に焦点をあてて―

　　This paper discusses the vulnerability of migrant women based on literature and statistics of international and domestic organizations. Migrant women are vulnerable to gender discrimination and violence. With the feminization of migration in globalized societies, this discrimination and violence has increased and become more salient.　　Migrant women who live in Japan experience vulnerability caused by barriers of culture and language, gender discrimination and violence, poverty facing single-mother households, and by lack of support for childrearing families. In providing support for migrant women, it is not entirely accurate to attribute problems solely to the idea that the vulnerability among migrant women is caused by their not being Japanese.　　In Japan, Migrant women’s vulnerability consists of various factors such as poor working environment, the cultural and linguistic barriers many migrants face, lack of support for families with children, and poverty in general. Therefore, in order for effective support to be provided for migrant women, public social services to deal with issues of childcare, poverty, and gender related problems should be developed. Services designed specifically to help migrant women and other non-Japanese residents should be developed as well

Cloning and sequence analysis of complementary DNA encoding a precursor for chicken natriuretic peptide

AbstractChicken α-natriuretic peptide (α-chNP) has been identified in chicken heart, which showed higher homology to brain natriuretic peptide (BNP) than to atrial natriuretic peptide (ANP) [1]. Complementary DNA (cDNA) clone encoding a chNP precursor (pre-chNP) precursor (pre-chNP) was isolated from cardiac cDNA library and sequenced. Pre-chNP was 140-residue signal peptide at the N-terminus and α-chNP at the C-terminus, and did not exhibit high homology to poreine BNP except for the C-terminal region. However, a characteristic AT-rich nucleotide sequence commonly found in mammalian BNPs was also present in the 3′-untranslated region. Thus, chNP is concluded to be classified into the BNP-typ

Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system

The pathogenic bacterium Shigella flexneri uses a type III secretion system to inject virulence factors from the bacterial cytosol directly into host cells. The machinery that identifies secretion substrates and controls the export of extracellular components and effector proteins consists of several inner-membrane and cytoplasmic proteins. One of the inner membrane components, Spa40, belongs to a family of proteins proposed to regulate the switching of substrate specificity of the export apparatus. We show that Spa40 is cleaved within the strictly conserved amino acid sequence NPTH and substitution of the proposed autocatalytic residue abolishes cleavage. Here we also report the crystal structure of the cytoplasmic complex Spa40C and compare it with the recent structures of the homologues from Escherichia coli and Salmonella typhimurium. These structures reveal the tight association of the cleaved fragments and show that the conserved NPTH sequence lies on a loop which, when cleaved, swings away from the catalytic N257 residue, resulting in different surface features in this region. This structural rearrangement suggests a mechanism by which non-cleaving forms of these proteins interfere with correct substrate switching of the apparatus

Urban and Industrial Impacts on Rural India : A Case Study of Suburban Village in Delhi Metropolitan Area

The urbanization and industrialization in India has progressed rapidly since the opening policy of the economy started. The industrialization has made great impacts on rural Indian villages, particularly on their social structure and stratification. The purpose of this study is to reveal the influences of the urbanization and industrialization on rural villages in India. It focuses on the economic aspect as well as the demographic, politic, administrative and social aspects of the change, based on the result of census survey and intensive survey carried out in 1997. The caste system is taken as a criterion to analyze this effect. R. village in the Gotama Buddha Nagar District, Utter Pradesh, is chosen as a sample village. This village is multi-caste society, consisting with wide range of caste classes from general castes to the Schedule Castes. During the 1950's and 60's, R village was still underdeveloped in spite of the condition that it was closed to Delhi, the capital of India. The Yamuna River, flowing between this village and Delhi, often flooded by the monsoon rain, and it gave serious damages to the village. The Green Revolution encouraged by the government was being spread around this area at the end of the 60's, but the village was unable to receive its effect because of the frequent floods. However, in the 70's, there was a turning point in that situation. Firstly, an embankment was constructed along the Yamuna River. This made possible for the village to accept the Green Revolution; soon, well irrigation was made and High Yield Varieties were planted. Secondly, the construction of NOIDA (New Okhla Industrial Development Authority), one of the biggest industrial estates in Utter Pradesh, began in 1977. This brought job opportunities to the lower caste villagers who had had no option except doing agricultural laborwork or craftman-work under the jajmani system. In the 80's, the opportunities of getting jobs in NOIDA increased. One of the government policies against the social inequality called the Res